1. Field of the Invention
The present invention relates to an engine generator adapted to be used as an electric power source for outdoor works and lighting, and particularly to an engine generator of a vertical shaft type having a work generator arranged at the upper side of an engine with a vertical crank shaft.
2. Prior Art
It is known in the art that an engine generator which uses an engine of a vertical crank shaft type has so far been disclosed, for example in Japanese Provisional Patent Publication No. 39933 of 1984, wherein a work generator is arranged at the underside of the engine. In this case, following problems are encountered with said such engine generator. That is, if engine oil leaks, the leaked oil is apt to flow into the interior of the generator to cause an insulation deterioration. And also the vibration of the engine generator is apt to be enlarged because the vibromotive position by the engine becomes higher than the gravity center of the whole engine generator, namely gets far from the support foot thereof on earth.
Therefore, the applicant (the assignee) of the present invention has disclosed in Japanese Utility Model Publication No. 77727 of 1985 an improved engine generator which has a generator arranged at the upper side of a forcedly air-cooled engine of a vertical crank shaft type.
In the engine generator disclosed in said publication and shown in FIG. 4, the generator 52 of an interiorly ventilated type is arranged at the upper side of the forcedly air cooled engine 50 of a vertical crank shaft type having a chamber 51 for a cooling fan provided at the upper portion thereof with the generator 52 aligned coaxially to the output shaft 53 of the engine 50, and there are provided with an air suction opening 55 at the upper portion of the generator casing 54 as well as an air exhaust opening 56 at the lower surface thereof 54 so that a cooling air sucked through the air suction opening 55 may be supplied downwards to the engine side by way of the interior of the generator.
In such conditions, since the virbomotive position becomes lower than the gravity center of the whole engine generator, the engine generator gets more stable sufficient to make the vibration thereof less.
However, in this prior case, since the cooling for the engine generator is carried out so as to cool the interior of the generator and the circumference of the engine by the downward flow of the cooling air supplied from the upper side thereof, the air discharged from the engine portion goes up along the engine generator due to its elevated temperature and is sucked again from the air suction opening provided at the upper portion of the generator. Hence, the cooling efficiency for the engine generator gets worse. Further, since the air suction opening is provided at the upper portion of the generator, dust and drops of water such as rain are apt to enter into the generator through the opening.